re: They are sticking with Biden because they are rigging the 2024 election.

It's never too late, DNC makes their own rules.
His dementia riddled arse makes cheating harder. They'll have to cheat twice as much this time around and they pulled all the stops last time, and more people are watching for it this time.
They'd love to replace him but he won't leave voluntarily. They're sick of him too but he won't bow out. They can't just boot him because they're involved in his corruption.
He has to agree to leave and protect their secrets or they'll have to kill him.

Or.. cheat but prepare for a loss. They'll focus on attacking and blocking Trump's presidency and prepare for '26 and '28. There isn't a final WIN for anyone.